Hydraulic piston machines are utilized, for example, in hydrostatic mechanical power split transmissions for the hydraulic power branch to vary continuously the transmission ratio. For this purpose, hydraulic piston machines need adjusting devices by means of which the swept volume of the piston machines is adjusted.
DE 42 06 023 A1 discloses a continuously variable hydrostatic mechanical power split transmission comprising hydraulic piston machines and adjusting devices by means of which the piston machines can be continuously adjusted. The adjusting device comprises control elements by means of which the piston machines can be controlled. In order to protect the system from overload, the adjusting device is provided with a pressure relief valve by means of which the maximum pressure can be limited. When the pressure relief valve is activated, the energy is converted into heat which must be released by means of a radiator.